++ed by:

1 non-PAUSE user.

Matthias Bloch
and 4 contributors

NAME

Data::Processor - Transform Perl Data Structures, Validate Data against a Schema, Produce Data from a Schema, or produce documentation directly from information in the Schema.

SYNOPSIS

  use Data::Processor;
  my $schema = {
    section => {
        description => 'a section with a few members',
        error_msg   => 'cannot find "section" in config',
        members => {
            foo => {
                # value restriction either with a regex..
                value => qr{f.*},
                description => 'a string beginning with "f"'
            },
            bar => {
                # ..or with a validator callback.
                validator => sub {
                    my $self   = shift;
                    my $parent = shift;
                    # undef is "no-error" -> success.
                    no strict 'refs';
                    return undef
                        if $self->{value} == 42;
                }
            },
            wuu => {
                optional => 1
            }
        }
    }
  };

  my $p = Data::Processor->new($schema);

  my $data = {
    section => {
        foo => 'frobnicate',
        bar => 42,
        # "wuu" being optional, can be omitted..
    }
  };

  my $error_collection = $p->validate($data, verbose=>0);
  # no errors :-)

  # in case of errors:
  # ------------------
  # print each error on one line.
  say $error_collection;

  # same
  for my $e ($error_collection->as_array){
      say $e;
      # do more..
  }

DESCRIPTION

Data::Processor is a tool for transforming, verifying, and producing Perl data structures from / against a schema, defined as a Perl data structure.

METHODS

new

 my $processor = Data::Processor->new($schema);

optional parameters: - indent: count of spaces to insert when printing in verbose mode. Default 4 - depth: level at which to start. Default is 0. - verbose: Set to a true value to print messages during processing.

validate Validate the data against a schema. The schema either needs to be present already or be passed as an argument.

 my $error_collection = $processor->validate($data, verbose=>0);

validate_schema

check that the schema is valid. This method gets called upon creation of a new Data::Processor object.

 my $error_collection = $processor->validate_schema();

merge_schema

merges another schema into the schema (optionally at a specific node)

 my $error_collection = $processor->merge_schema($schema_2);

merging rules: - merging transformers will result in an error - merge checks if all merged elements match existing elements - non existing elements will be added from merging schema - validators from existing and merging schema get combined

schema

Returns the schema. Useful after schema merging.

transform_data

Transform one key in the data according to rules specified as callbacks that themodule calls for you. Transforms the data in-place.

 my $validator = Data::Processor::Validator->new($schema, data => $data)
 my $error_string = $processor->transform($key, $schema_key, $value);

This is not tremendously useful at the moment, especially because validate() transforms during validation.

make_data

Writes a data template using the information found in the schema.

 my $data = $processor->make_data(data=>$data);

make_pod

Write descriptive pod from the schema.

 my $pod_string = $processor->make_pod();

SCHEMA REFERENCE

Top-level keys and members

The schema is described by a nested hash. At the top level, and within a members definition, the keys are the same as the structure you are describing. So for example:

 my $schema = {
     coordinates => {
         members => {
             x => {
                 description => "the x coordinate",
             },
             y => {
                 description => "the y coordinate",
             },
         }
     }
 };

This schema describes a structure which might look like this:

 { coordinates => { x => 1, y => 2} }

Obviously this can be nested all the way down:

  my $schema = {
     house => {
        members => {
            bungalow => {
                members => {
                    rooms => {
                      #...
                    }
                }
            }
        }
     }
  };

array

To have a key point to an array of things, simply use the array key. So:

 my $schema = {
    houses => {
       array => 1,
    }
 };

Would describe a structure like:

 { houses => [] }

And of course you can nest within here so:

 my $schema = {
    houses => {
       array => 1,
       members => {
           name => {},
           windows => {
               array => 1,
           }
       },
    },
 };

Might describe:

 {
   houses => [
      { name => 'bob',
        windows => []},
      { name => 'harry',
        windows => []},
   ]
 }

description

The description key within a definition describes that value:

 my $schema = {
     x => { description => 'The x coordinate' },
 };

error_msg

The error_msg key can be set to provide extra context for when a value is not found or fails the value test.

optional

Most values are required by default. To reverse this use the "optional" key:

 my $schema = {
     x => {
       optional => 1,
     },
     y => {
       # required
     },
 };

regex

Treating regular expressions as keys

If you set "regex" within a definition then it's key will be treated as a regular expression.

 my $schema = {
    'color_.+' => {
       regex => 1
    },
 };
 my $data = { color_red => 'red', color_blue => 'blue'};
 Data::Processor->new($schema)->validate($data);

transformer

transform the data for further processing

Transformer maps to a sub ref which will be passed the value and the containing structure. Your return value provides the new value.

 my $schema = {
    x => {
        transformer => sub{
           my( $value, $section ) = @_;
           $value = $value + 1;
           return $value;
        }
    }
 };
 my $data = { x => 1 };
 my $p = Data::Processor->new($schema);
 my $val = Data::Processor::Validator->new( $schema, data => $data);
 $p->transform_data('x', 'x', $val);
 say $data->{x}; #will print 2

If you wish to provide an error from the transformer you should die with a hash reference with a key of "msg" mapping to your error:

 my $schema = {
    x => {
         transformer => sub{
             die { msg => "SOMETHING IS WRONG" };
         }
    },
 };

 my $p = Data::Processor->new($schema);
 my $data = { x => 1 };
 my $val = Data::Processor::Validator->new( $schema, data => $data);
 my $error = $p->transform_data('x', 'x', $val);

 say $error; # will print: error transforming 'x': SOMETHING IS WRONG

The transformer is called before any validator, so:

 my $schema = {
    x => {
        transformer => sub{
           my( $value, $section ) = @_;
           return $value + 1;
        },
        validator => sub{
           my( $value ) = @_;
           if( $value < 2 ){
              return "too low"
           }
        },
    },
 };
 my $p = Data::Processor->new( $schema );
 my $data = { x => 1 };
 my $errors = $p->validate();
 say $errors->count; # will print 0
 say $data->{x}; # will print 2

value

checking against regular expression

To check a value against a regular expression you can use the value key within a definition, mapped to a quoted regex:

 my $schema = {
     x => {
        value => qr{\d+}
     }
 };

validator

checking more complex values using a callback

To conduct extensive checks you can use validator and provide a callback. Your sub will be passed the value and it's container. If you return anything it will be regarded as an error message, so to indicate a valid value you return nothing:

 my $schema = {
    bob => {
      validator => sub{
         my( $value, $section ) = @_;
         if( $value ne 'bob' ){
            return "Bob must equal bob!";
         }
         return;
      },
    },
 };
 my $p = Data::Processor->new($schema);
 # would validate:
 $p->validate({ bob => "bob" });
 # would fail:
 $p->validate({ bob => "harry"});

See also Data::Processor::ValidatorFactory

Validator objects

Validator may also be an object, in this case the object must implement a "validate" method.

The "validate" method should return undef if valid, or an error message string if there is a problem.

 package FiveChecker;

 sub new {
     bless {}, shift();
 }

 sub validate{
     my( $self, $val ) = @_;
     $val == 5 or return "I wanted five!";
     return;
 }
 package main;

 my $checker = FiveChecker->new;
 my $schema = (
     five => (
         validator => $checker,
     ),
 );
 my $dp = Data::Processor->new($schema);
 $dp->validate({five => 6}); # fails
 $dp->validate({five => 5}); # passes

You can for example use MooseX::Types and Type::Tiny type constraints that are objects which offer validate methods which work this way.

 use Types::Standard -all;

 # ... in schema ...
      foo => {
          validator => ArrayRef[Int],
          description => 'an arrayref of integers'
      },

AUTHOR

Matthias Bloch <matthias.bloch@puffin.ch>

COPYRIGHT

Copyright 2015- Matthias Bloch

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.